function getDistance(lat1,lng1,lat2,lng2){
    const R=6378137
    let dis=0
    let radLat1 = toRadians(lat1)
    let radLat2 = toRadians(lat2)
    let deltaLat = radLat1-radLat2
    let deltaLng = toRadians(lng1) - toRadians(lng2)
    dis = 2 * R * Math.asin(Math.sqrt(Math.pow(Math.sin(deltaLat/2),2)
    + Math.cos(radLat1) * Math.cos(radLat2)*Math.pow(Math.sin(deltaLng/2),2)))
    return dis
}
function toRadians(d){
    return d * Math.PI/180
}
module.exports={
    getDistance
}
